Which of the following is a key feature of Alzheimer’s disease?

Memory loss is a key feature of Alzheimer’s disease and often serves as one of the earliest and most prominent symptoms. In Alzheimer’s, patients typically experience difficulty remembering recent events, learning new information, and recalling previously learned facts. This condition primarily affects the areas of the brain associated with memory and cognition, leading to progressive impairment.

The other options represent symptoms or conditions that are not characteristic of Alzheimer’s disease. Extrapyramidal symptoms are often associated with movement disorders, such as Parkinson's disease, which involve motor control issues and are not typical of Alzheimer’s. Increased reflexes can indicate neurological issues but are not specific to Alzheimer’s. Severe headaches may occur in various conditions but do not represent a primary indicator of Alzheimer's disease. Thus, memory loss is the defining cognitive decline seen in individuals with Alzheimer's.